Dorner, the 33-year-old former naval and Los Angeles Police Department officer turned triple-murder suspect, had been at the center of a massive manhunt stretching from the San Bernardino Mountains in California—where his burned-out pickup truck was found last week—to the Mexican border.

In a manifesto posted online earlier this month, Dorner promised "unconventional and asymmetrical warfare" against the LAPD, which fired him in 2008.

The defiant digital display during the pursuit for Dorner on Tuesday recalled the real-life drama of June 17, 1994, when hundreds of people lined Los Angeles freeways to cheer on O.J. Simpson in a white Ford Bronco as police trailed behind.

But support for Dorner—who police say shot two officers during a gun battle near Big Bear, Calif., on Tuesday, killing one—led to a swift backlash that, in part, helped keep #TeamDorner trending.

"Reports that the officer killed by Dorner earlier was married and expecting a child," A. J. Delgado tweeted. "#TeamDorner, you cheer for this guy?"

"Proposal," Derek Hunter wrote. "Anyone identified tweeting support for #TeamDorner gets their 911 calls ignored 1 hour for each tweet for the rest of their lives."

"You don't have to be religious to believe there is something very, very sick about our culture right now. #TeamDorner," David Burge wrote.

But even before Wednesday's shootout, several Facebook pages supporting his cause had been gathering steam.

One, called "We Are All Chris Dorner," had more than 2,800 "likes" before the cabin Dorner was suspected to be in began to burn. It now has more 3,700.

"Christopher Jordan Dorner is the victim of a manhunt and smear campaign," its description reads. "[Five] years ago he was fired from the LAPD for seeking to expose corruption within it."

The Facebook page, launched last week, includes links to statements of support and a link to Dorner's "complete and 'uncensored'" manifesto, encouraging followers to "do your own research and draw your own conclusions."

During Tuesday's standoff, the operators of the "We Are All Chris Dorner" page even suggested supporters "hijack" the State of the Union hashtag on Twitter:

If you like to tweet and tweet about Dorner, consider adding the hashtag #SOTU to your posts. Let's hijack that s--- and show America where we stand and why. F--- the police state.

Another Dorner "fan" page had more than 1,000 "likes" before Tuesday's pursuit. It now has more than 2,000.